A malfunctioning float valve caused a fuel tank on the roof to overflow Sunday, spilling 100 to 200 gallons of heating oil inside the eight-story state office building at Third and Main streets downtown. The building, which some call the Spam Can, houses some state employees and private tenants.

A spokesman for the governor said safety inspectors Monday ruled out the danger of explosion but measured harmful levels of benzene in the building and closed it to everyone except cleanup crews trained to respond to petroleum spills.

An owner of an environmental consulting firm hired to clean up the mess said today the fumes had dropped to levels safe enough for his crew to wear only filtered masks, instead of air tanks. Tom Carson, of Carson Dorn Inc., said he hoped to have his crew inside the building by this afternoon to remove carpeting, gypsum wallboard and other materials fouled in the spill. The plan is to dump the materials into double bags, then into fish totes and probably burn the contents in an incinerator, he said.

The company won't know how long cleanup will take until crews peel back the wallboard and see whether the fuel seeped into the foam insulation inside the west wall of the building.

"The issue in the long term is how much wall material will have to come down to control the odor so people are happy being back in there," said Carson. "We could (have) to take all the insulation out. Right now, we just don't know."

Meanwhile, the state continued its search for alternate office space for the 140 people, mostly state employees, shut out of the building. Jim Duncan, commissioner of the Department of Administration, said some people have relocated to other state buildings, but many have no place to work.

Affected state employees were granted paid leave Monday and today, and the state has set up a recorded message at 465-5789 with further instructions for dislocated workers. The state also is posting information on GCI's scanner channel, and Duncan said supervisors should be calling their employees to let them know whether to stay home or report to work elsewhere. He advised state workers to be on call.

"Be ready because the commitment we have is to try to relocate people as quickly as we can into acceptable office space so they can get back to doing their job," Duncan said.

He said the state is evaluating the amount of space available downtown but that any relocation effort will hinge on whether the move is for the long term or short term. Duncan said the state probably will not know until the end of the week how long the cleanup will take.

Some people, including private tenants, have said they want to retrieve papers from the building, and Duncan said the state may ask the cleanup crew to help recover documents if the building remains off-limits to employees this week.

"Clearly there's undoubtedly some folks who had some important work going on. We need to try to accommodate that," Duncan said.

The largest private tenant might be back in the building by late today. The Alaska State Employees Federal Credit Union is located on the ground floor, which escaped damage but reeks of diesel. CEO Sharon Kelly said she was allowed to enter the area this morning and although she noticed a strong smell, the state has told her the fumes are within safe levels.

The credit union Monday temporarily moved to its administrative building by the Douglas Bridge, and Kelly said she might continue operations there even after the Main Street branch reopens, so its six employees and 5,000 Juneau customers will have the option of avoiding the fumes.

"Some people might find it offensive. It's not hazardous, it just might affect some people differently," Kelly said.

Bob King, a spokesman for Gov. Tony Knowles, said the state does not have an estimate yet on the cost of the cleanup, but the building is insured with a $1 million deductible. King said the 50-gallon fuel tank is on top of the building because the furnace is there. The building's main fuel tank is on a lower level. King said the upper tank holds just enough diesel to heat the building for one day, and that configuration is not uncommon in state buildings, including the Dimond Courthouse.